audit: remove audit_finish_fork as it can't be called

Audit entry,always rules are not allowed and are automatically changed in
exit,always rules in userspace.  The kernel refuses to load such rules.

Thus a task in the middle of a syscall (and thus in audit_finish_fork())
can only be in one of two states: AUDIT_BUILD_CONTEXT or AUDIT_DISABLED.
Since the current task cannot be in AUDIT_RECORD_CONTEXT we aren't every
going to actually use the code in audit_finish_fork() since it will
return without doing anything.  Thus drop the code.

Signed-off-by: Eric Paris <eparis@redhat.com>

include/linux/audit.h

@@ -415,7 +415,6 @@ extern int audit_classify_arch(int arch);
 #ifdef CONFIG_AUDITSYSCALL
 /* These are defined in auditsc.c */
 				/* Public API */
-extern void audit_finish_fork(struct task_struct *child);
 extern int  audit_alloc(struct task_struct *task);
 extern void __audit_free(struct task_struct *task);
 extern void __audit_syscall_entry(int arch,
@@ -586,7 +585,6 @@ static inline void audit_mmap_fd(int fd, int flags)
 extern int audit_n_rules;
 extern int audit_signals;
 #else /* CONFIG_AUDITSYSCALL */
-#define audit_finish_fork(t)
 #define audit_alloc(t) ({ 0; })
 #define audit_free(t) do { ; } while (0)
 #define audit_syscall_entry(ta,a,b,c,d,e) do { ; } while (0)